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Abstract:

A trans-fill method and system comprising obtaining therapeutic gas from
a therapeutic gas source, compressing the therapeutic gas from the
therapeutic gas source in at least two stages to create an intermediate
therapeutic gas stream and a high pressure therapeutic gas stream,
supplying therapeutic gas to a patient from the intermediate therapeutic
gas stream, and filling a cylinder with the therapeutic gas from the high
pressure therapeutic gas stream substantially simultaneously with
supplying therapeutic gas to the patient.

Claims:

1. A trans-fill system comprising: a compression system adapted to
receive a low pressure oxygen-enriched gas stream at an inlet of the
trans-fill system, the compression system having a first compression
stage that creates an intermediate pressure oxygen-enriched gas stream
from the low pressure oxygen-enriched gas stream, and second compression
stage that creates a high pressure oxygen-enriched gas stream from the
intermediate pressure oxygen-enriched gas stream; a conserver coupled to
the intermediate pressure therapeutic gas stream, the conserver adapted
to deliver a bolus of therapeutic gas to a patient during at least a
portion of an inhalation cycle of the patient; and a fill port
operatively coupled to the high pressure therapeutic gas stream, wherein
filling a storage vessel via the fill port is provided substantially
simultaneously with providing therapeutic gas to the patient via the
conserver.

2. The trans-fill system as defined in claim 1, wherein the low pressure
gas stream has a pressure of approximately 3.5 pounds per square inch
(PSI) to approximately 6 PSI.

3. The trans-fill system as defined in claim 1, wherein the intermediate
pressure therapeutic gas stream has a pressure of approximately 20 pounds
per square inch (PSI) to 35 PSI.

4. The trans-fill system as defined in claim 1, wherein the high pressure
therapeutic gas stream has a pressure of approximately 2700 pounds per
square inch (PSI).

5. The trans-fill system as defined in claim 1, wherein the compression
system further comprises a diaphragm pump having an inlet coupled to the
low pressure therapeutic gas stream, and wherein the diaphragm pump
creates the intermediate pressure therapeutic gas stream.

6. The trans-fill system as defined in claim 5, wherein the diaphragm
pump creates the intermediate pressure therapeutic gas stream having a
pressure of approximately 20 pounds per square inch (PSI) to
approximately 35 PSI.

7. The trans-fill system as defined in claim 1, wherein the trans-fill
system does not utilize a buffer tank to buffer oxygen-enriched
therapeutic gas provided at the inlet.

8. The trans-fill system as defined in claim 1, further comprising: a gas
monitoring device coupled to the oxygen-enriched therapeutic gas provided
at the inlet, the gas monitoring device operable to detect purity of the
therapeutic gas, and wherein the trans-fill system does not provide
therapeutic gas to the storage vessel if the oxygen concentration of the
oxygen-enriched therapeutic gas falls below 90%.

9. The trans-fill system as defined in claim 8, wherein the gas
monitoring device further comprises an oxygen-specific sensor.

10. The trans-fill system as defined in claim 8, wherein the gas
monitoring device further comprises a density sensor.

11. A trans-fill system for use with an oxygen concentrator that
generates a low pressure oxygen-enriched therapeutic gas stream from
ambient gas, the trans-fill system comprising: a compression system
adapted to receive the low pressure oxygen-enriched therapeutic gas
stream at an inlet of the trans-fill system, the compression system
having a first compression stage coupled to the low pressure
oxygen-enriched therapeutic gas stream that creates an intermediate
pressure oxygen-enriched therapeutic gas stream, and a second compression
stage coupled to the intermediate pressure oxygen-enriched therapeutic
gas stream that creates a high pressure oxygen-enriched therapeutic gas
stream; a conserver coupled to the intermediate pressure oxygen-enriched
therapeutic gas stream, the conserver adapted to deliver a bolus of
oxygen-enriched therapeutic gas to a patient during at least a portion of
an inhalation cycle of the patient; an adjustable flow restriction device
fluidly coupled to the low pressure oxygen-enriched therapeutic gas
stream, and wherein the trans-fill system provides oxygen-enriched
therapeutic gas from the high pressure oxygen-enriched therapeutic gas
stream to a storage vessel and also substantially simultaneously one of:
(a) provides oxygen-enriched therapeutic gas to the patient through the
conserver, or (b) provides oxygen-enriched therapeutic gas to the patient
through the adjustable flow restriction device.

12. The trans-fill system as defined in claim 11, wherein the low
pressure oxygen-enriched therapeutic gas stream has a pressure of
approximately 3.5 pounds per square inch (PSI) to approximately 6 PSI.

13. The trans-fill system as defined in claim 11, wherein the
intermediate pressure oxygen-enriched therapeutic gas stream has a
pressure of approximately 20 pounds per square inch (PSI) to 35 PSI.

14. The trans-fill system as defined in claim 11, wherein the high
pressure oxygen-enriched therapeutic gas stream has a pressure of
approximately 2700 pounds per square inch (PSI).

15. The trans-fill system as defined in claim 11, further comprising a
humidifier system fluidly coupled to the low pressure oxygen-enriched
therapeutic gas stream.

16. A system comprising: means for generating a low pressure
oxygen-enriched therapeutic gas stream from ambient gas; first means for
compressing the low pressure oxygen-enriched therapeutic gas stream to
create an intermediate pressure oxygen-enriched therapeutic gas stream;
second means for compressing the intermediate pressure oxygen-enriched
therapeutic gas stream to create a high pressure oxygen-enriched
therapeutic gas stream; and means for delivering oxygen-enriched
therapeutic gas to a patient from the intermediate pressure
oxygen-enriched therapeutic gas stream substantially simultaneously with
providing the high pressure oxygen-enriched therapeutic gas stream to a
storage vessel.

17. The system as defined in claim 16, further comprising: means for
executing programs electrically coupled to the first means for
compressing and means for delivering a bolus, wherein the means for
executing programs controls the first means for compressing to control a
pressure of the intermediate pressure oxygen-enriched therapeutic gas
stream generated by the first means for compressing.

18. The system as defined in claim 17, further comprising: means for
monitoring an oxygen concentration of oxygen-enriched therapeutic gas,
and means for sensing fluidly coupled to the oxygen-enriched therapeutic
gas and electrically coupled to the means for executing; wherein the
means for executing refrains from filling the cylinder when the means for
sensing detects that an oxygen concentration of the oxygen-enriched
therapeutic gas falls below approximately 90%.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a Continuation under 35 U.S.C. §121 of
U.S. patent application Ser. No. 11/037,523, filed 18 Jan. 2005, the
contents of which is incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not applicable.

BACKGROUND OF THE INVENTION

[0003] 1. Field of the Invention

[0004] Embodiments of the present invention are directed to delivery of
therapeutic gas to a patient and substantially simultaneously filling
portable cylinders.

[0005] 2. Background of the Invention

[0006] Many patients with lung and/or cardiovascular problems are required
to breathe therapeutic gas in order to obtain sufficient dissolved oxygen
in their blood stream. In home environments, patients may have a
pressure-swing absorption (PSA) system comprising a compressor that
forces atmospheric air through one or more molecular sieves. The sieve
material traps nitrogen, and thus the gas exiting a molecular sieve has
an increased oxygen content-oxygen-enriched gas. For this reason, PSA
systems may be referred to as oxygen concentration systems and/or oxygen
concentrators. While, the oxygen-enriched gas exiting a molecular sieve
bed has a pressure of approximately 20 pounds per square inch (PSI), most
oxygen concentrators regulate the pressure and continuously deliver
therapeutic gas to the patient at approximately 5 PSI. Oxygen-enriched
gas at the pressure that the gas exits the molecular sieve bed is not
made available to the patient. Stated otherwise, most oxygen
concentrators do not have a port from which oxygen-enriched gas at
approximately 20 PSI may be supplied.

[0007] PSA systems, however, are not generally portable. So that patients
may be ambulatory, therapeutic gas may be delivered from a portable
cylinder. A portable cylinder, however, provides only limited volume, and
therefore periodically needs to be refilled. While it is possible to have
these cylinders exchanged or refilled by way of commercial home health
care services, some patients have systems within their homes which
perform a dual function: filling portable cylinders with oxygen-enriched
gas; and providing oxygen-enriched gas to the patient for breathing.
Systems such as these have come to be known as "trans-fill" systems.

[0008] Trans-fill systems need to produce oxygen-enriched gas having
pressure of approximately 2700 PSI to fill a portable cylinder to a full
state of approximately 2200 PSI. In order to achieve the pressure
sufficient to fill a cylinder, a compressor (also known in the art as an
intensifier) is used. However, 5 PSI oxygen-enriched gas may be too low
an inlet pressure for an intensifier to create sufficient pressure to
fill a portable cylinder. For this reason, related art trans-fill systems
are integral systems, combining an oxygen concentrator with an
intensifier. The intensifier is supplied oxygen-enriched gas at the
pressure the gas exits the molecular sieve bed, approximately 20 PSI, and
the patient is provided pressure regulated oxygen-enriched gas at
approximately 5 PSI. For example, U.S. Pat. No. 5,858,062 to McCulloh et
al. (assigned to Litton Systems, Inc. and thus hereinafter the "Litton
patent") discloses an integral system where oxygen-enriched gas exiting a
molecular sieve bed of an oxygen concentrator is applied to a plenum.
From the plenum, the oxygen-enriched gas is supplied to an intensifier,
and also from the plenum the pressure of the oxygen-enriched gas is
regulated and supplied to a patient port. Likewise, U.S. Pat. No.
5,988,165 to Richey, I I et al. discloses an integral system where, much
like the Litton patent, oxygen-enriched gas exiting a molecular sieve bed
of an oxygen concentrator is provided to a compressor, and regulated to 5
PSI before being provided to the patient.

[0009] Thus, what is needed is a trans-fill method and system that is not
constrained to having an integral oxygen concentrator, and thus could use
oxygen-enriched gas provided from any third party oxygen concentration
system or other source of oxygen-enriched gas.

SUMMARY OF SOME OF THE PREFERRED EMBODIMENTS

[0010] The problems noted above are solved in large part by a trans-fill
method and system. Some exemplary embodiments may be a method comprising
obtaining therapeutic gas from a therapeutic gas source, compressing the
therapeutic gas from the therapeutic gas source in at least two stages to
create an intermediate therapeutic gas stream and a high pressure
therapeutic gas stream, supplying therapeutic gas to a patient from the
intermediate therapeutic gas stream, and filling a cylinder with the
therapeutic gas from the high pressure therapeutic gas stream
substantially simultaneously with supplying therapeutic gas to the
patient.

[0011] Other illustrative embodiments are a trans-fill device comprising a
therapeutic gas inlet port that is supplied therapeutic gas from a
therapeutic gas source (at pressures of approximately 3.5 pounds per
square inch (PSI) to approximately 6 PSI), a patient port that supplies
therapeutic gas to a patient (wherein the patient port supplies the
therapeutic gas at a pressure of approximately 20 PSI to approximately 35
PSI, the therapeutic gas taken between a first and second compression
stage within the trans-fill device), and a cylinder fill outlet port that
supplies therapeutic gas to fill a cylinder to approximately 2200 PSI
substantially simultaneously with the patient port supplying therapeutic
gas to the patient.

[0012] Yet other exemplary embodiments are a trans-fill system comprising
a compression system coupled to oxygen-enriched therapeutic gas provided
at an inlet of the trans-fill system (the compression system having a
first compression stage which creates an intermediate pressure
therapeutic gas stream from the oxygen-enriched therapeutic gas at the
inlet, and a second compression stage which creates a high pressure
therapeutic gas stream from the intermediate pressure therapeutic gas
stream), and a conserver coupled to the intermediate pressure therapeutic
gas stream (the conserver delivers a bolus of therapeutic gas to a
patient during inhalation of the patient). The trans-fill system provides
therapeutic gas from the high pressure therapeutic gas stream to a
portable cylinder and also substantially simultaneously provides
therapeutic gas to the patient.

[0013] Yet other illustrative embodiments are a trans-fill system
comprising a compression system coupled to a low pressure therapeutic gas
stream provided at an inlet of the trans-fill system (the compression
system having a first compression stage coupled to the low pressure
therapeutic gas stream that creates an intermediate pressure therapeutic
gas stream, and a second compression stage coupled to the intermediate
pressure therapeutic gas stream that creates a high pressure therapeutic
gas stream), a conserver coupled to the intermediate pressure therapeutic
gas stream (the conserver delivers a bolus of therapeutic gas to a
patient during inhalation of the patient), and an adjustable flow
restriction device fluidly coupled to the low pressure therapeutic gas
stream. The trans-fill system provides therapeutic gas from the high
pressure therapeutic gas stream to a portable cylinder and also
substantially simultaneously one of: provides therapeutic gas to the
patient through the conserver; or provides therapeutic gas to the patient
through the adjustable flow restriction device.

[0014] The disclosed devices and methods comprise a combination of
features and advantages which enable it to overcome the deficiencies of
the prior art devices. The various characteristics described above, as
well as other features, will be readily apparent to those skilled in the
art upon reading the following detailed description, and by referring to
the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] For a detailed description of the preferred embodiments of the
invention, reference will now be made to the accompanying drawings in
which:

[0016] FIG. 1 illustrates a system for providing therapeutic gas to the
patient and for filling portable cylinders in accordance with at least
some embodiments of the invention; and

[0017] FIG. 2 illustrates a trans-fill system in accordance with
alternative embodiments.

NOTATION AND NOMENCLATURE

[0018] Certain terms are used throughout the following description and
claims to refer to particular system components. This document does not
intend to distinguish between components that differ in name but not
function.

[0019] In the following discussion and in the claims, the terms
"including" and "comprising" are used in an open-ended fashion, and thus
should be interpreted to mean "including, but not limited to . . . ".
Also, the term "couple" or "couples" is intended to mean either an
indirect or direct connection. Thus, if a first device couples to a
second device, that connection may be through a direct connection, or
through an indirect connection via other devices and connections.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Trans-fill systems in accordance with embodiments of the invention
comprise both electrical components and mechanical components. In order
to differentiate between electrical connections and fluid connections,
FIGS. 1 and 2 illustrate electrical connections between devices with
dash-dot-dash lines, and fluid connections, e.g. tubing connections
between devices, with solid lines.

[0021] FIG. 1 illustrates a trans-fill system in accordance with
embodiments of the invention. The trans-fill system 1000 comprises a
therapeutic gas inlet port 10 that couples to a source of therapeutic
gas. In accordance with at least some embodiments, the therapeutic gas
inlet port couples to an oxygen source or oxygen concentrator 12. The
oxygen concentrator 12 may be any suitable device for increasing the
oxygen content of therapeutic gas delivered to a patient. For example,
the oxygen concentrator 12 may be a pressure-swing absorption (PSA)
system having a plurality of molecular sieve beds operated in a parallel
relationship. In a PSA system, atmospheric air drawn through an air inlet
is compressed by a compressor internal to the oxygen concentrator 12 and
applied to a molecular sieve bed. In the sieve bed, nitrogen molecules
are trapped, and oxygen and argon molecules flow through substantially
unimpeded. By removing the nitrogen from the atmospheric air, the
concentration of oxygen in the gas exiting the sieve bed may be
relatively high, e.g. 90% oxygen or more. While coupling to a PSA system
is preferred, a trans-fill system in accordance with embodiments of the
invention may couple to any device or system capable of making and/or
delivering therapeutic gas.

[0022] In accordance with embodiments of the invention, the therapeutic
gas inlet port 10 accepts therapeutic gas from a low pressure therapeutic
gas stream having pressures of approximately 3.5 pounds per square inch
(PSI) to approximately 6 PSI, and preferably 5 PSI. Because trans-fill
system 1000 is capable of operating with therapeutic gas inlet pressures
in the 3.5 PSI to 6 PSI range, trans-fill system 1000 may couple to the
patient port of substantially any commercially available oxygen
concentrator, and thus the trans-fill system 1000 need not have an
integral oxygen concentrator 12.

[0023] In order to increase the pressure of the low pressure therapeutic
gas stream, trans-fill system 1000 comprises a compression system 14
which takes the low pressure therapeutic gas and increases the pressure
to a pressure sufficient to fill a cylinder, e.g., portable cylinder 16.
In accordance with at least some embodiments, the compression system 14
increases the pressure of the low pressure therapeutic gas stream to
create a high pressure therapeutic gas stream of approximately 2700 PSI,
e.g., at point 18. The high pressure therapeutic gas stream flows through
a flow restrictor 20 and then to the portable cylinder 16 by way of a
cylinder fill outlet port 21 and a cylinder fill connector 22. The flow
restrictor 20 may take any suitable form, e.g., an orifice plate or
possibly a section of tubing having relatively small internal diameter
(ID).

[0024] A compression system 14 in accordance with embodiments of the
invention comprises at least two stages. A first compression stage 24
increases the pressure of the low pressure therapeutic gas stream to
create an intermediate pressure gas stream of approximately 20 PSI to 35
PSI, with 20 PSI being preferred. The second compression stage 26
increases pressure of the intermediate pressure therapeutic gas stream to
create the high pressure therapeutic gas stream. In accordance with a
least some embodiments of the invention, the first compression stage 24
is a diaphragm pump (discussed more fully below), and therefore indeed
represents a single stage; however, though the illustrated embodiments of
FIG. 1 show only a first compression stage 24 and a second compression
stage 26, these stages themselves may comprise multiple compression
stages, and thus FIG. 1 should not be construed to limited the actual
number of compression stages contained within either of the illustrative
first compression stage 24 or second compression stage 26.

[0025] A trans-fill system in accordance with embodiments of the invention
has the ability to fill a portable cylinder 16, and also substantially
simultaneously provide therapeutic gas to a patient. In accordance with
at least some embodiments, therapeutic gas is provided to the patient
from the intermediate pressure therapeutic gas stream created by the
first compression stage 24. In particular, the intermediate pressure
therapeutic gas stream fluidly couples to a conserver system 28. The
conserver system 28 fluidly couples to a patient by way of a patient port
30, e.g., a DISS port coupled to a nasal cannula. The conserver system 28
senses an inhalation of a patient and provides a bolus of therapeutic gas
on substantially each inhalation--conserve mode operation. Supplying a
conserver system with oxygen-enriched gas in the illustrative 20 PSI to
33 PSI range advantageously increases the efficiency of the conserving
system 28, and also advantageously increases the possible distance
between the trans-fill device and the patient. For example, having an
intermediate pressure therapeutic gas stream in the illustrative 20 PSI
to 35 PSI range allows for conserve mode operation with tubing lengths
between the trans-fill device and nasal cannula of the patient of 50 feet
or more. U.S. patent Ser. No. 10/287,899, titled, "Therapeutic Gas
Conserver and Control," incorporated by reference herein as if reproduced
in full below, discloses a conserver system with extended range
capabilities.

[0026] Trans-fill systems in accordance with embodiments of the invention
also comprise a processor 32. The processor 32 may be a microcontroller,
and therefore the microcontroller may be integral with read only memory
(ROM) 34, random access memory (RAM) 36, a digital output (DO) module 38,
an analog-to-digital converter (A/D) 40 and a pulse width modulation
(PWM) module 42. Although a microcontroller may be preferred because of
the integrated components, in alternative embodiments the processor 32
may be implemented as a standalone central processing unit in combination
with individual ROM, RAM, DO, A/D and PWM devices.

[0027] The ROM 34 stores instructions executable by the processor 32. In
particular, the ROM 34 comprises software programs that implement control
of the compression system 14, as well as control of the conserver system
28. The RAM 36 is the working memory for the processor 32, where data is
temporarily stored and from which instructions are executed. Processor 32
couples to other devices within the trans-fill system by way of the
analog-to-digital converter 40, the digital output module 38, and the
pulse-width module 42.

[0028] Pressure sensor 44 fluidly couples to the intermediate pressure
therapeutic gas stream, and electrically couples to the analog-to-digital
converter 40. Pressure sensor 44 may be a part no. MPX4250DP pressure
transducer available from Motorola, Inc. of Schaumburg, Ill. Software
executed by processor 32 reads the pressure of the intermediate pressure
therapeutic gas stream using pressure sensor 44. If the pressure is
greater than a set point pressure, then the processor 32 changes a speed
command coupled to the first compression stage 24, possibly by way of
pulse-width modulation module 42. In accordance with embodiments of the
invention, the first compression stage 24 is a diaphragm pump having part
number D827-23-01 produced by Hargraves Technology Corporation of
Mooresville, N.C. The illustrative Hargraves diaphragm pump is a combined
diaphragm pump, motor and motor control system that controls speed of
oscillation of the diaphragm (and therefore outlet pressure/flow) based
on a 0 volt to 5 volt control input.

[0029] Thus, in accordance with these embodiments of the invention,
processor 32, executing a program, reads the pressure of the intermediate
pressure therapeutic gas stream, and produces a pulse-width modulated
output through the module 42 that electrically couples to the control
input of the first compression stage 24. In order to convert the
pulse-width modulated output to a 0 volt to 5 volt control signal, the
trans-fill system 1000 has an averaging circuit 46. Averaging circuit 46
comprises a diode in combination with a RC filter, which takes the pulse
width modulated signal created by the module 42 and creates a 0 volt to 5
volt control signal applied to the diaphragm pump. In alternative
embodiments of the invention, the processor 32 directly creates the 0
volt to 5 volt control signal by use of a digital-to-analog (D/A)
converter (not specifically shown). In yet further alternative
embodiments, a different first compression stage device or devices may be
used, and these devices may utilize different types of control inputs.
Inasmuch as the pressure of the intermediate pressure therapeutic gas
stream is controlled by the first compression stage 24, the pressure of
the therapeutic gas stream may be outside the preferred 3.5 PSI to 6 PSI
range without departing from the scope and spirit of the invention.

[0030] The compression system 14 in accordance with embodiments of the
invention also comprises a second compression stage 26. As discussed
above, the second compression stage takes the intermediate pressure
therapeutic gas stream and produces the high pressure therapeutic gas
stream. The second compression stage 26 is also controlled by the
processor 32. In accordance with some embodiments of the invention, the
second compression stage 26 is a compressor or intensifier, such as a
part number 2003336-1 intensifier (itself having multiple stages)
produced through Chad Therapeutics, Inc. of Chatsworth, Calif. In
alternative embodiments, the second compression stage is a wobble-piston
compressor, such as described in U.S. Pat. No. 6,302,107, or a linear
cylinder used as a compressor. Inasmuch as the pressure of the
intermediate pressure therapeutic gas stream is controlled, the second
compression stage 26 need not necessarily have the ability to produce a
variable outlet pressure, and may be controlled as an on-off device. In
these embodiments then, processor 32, executing a program, selectively
turns on and off the second compression stage 26 by selectively asserting
and deasserting a digital output from digital output module 38.

[0031] In accordance with at least some embodiments, the times at which
the illustrative second compression stage is operational is a function of
both the oxygen concentration of the low pressure therapeutic gas stream,
and the status of the fill of the portable cylinder 16. With regard to
oxygen concentration, a gas sense device 48 fluidly couples to the
therapeutic gas inlet port 10 by way of a flow restriction device 50. In
some embodiments, the gas sense device 48 is an oxygen-selective sensor,
such as sensors based on zirconium oxide, galvanic, or paramagnetic
technologies. If the gas sense device 48 is an oxygen-selective sensor,
the device analyzes the actual percentage of oxygen in the gas.
Alternatively, the gas sense device 48 is a time-of-flight density sensor
that measures density, and thus purity, of a gas stream. By taking a
relatively small sample of the therapeutic gas provided at the
therapeutic gas inlet port, e.g. 5 cubic centimeters (cc) per minute, the
gas sense device 48 determines the oxygen concentration or purity of the
therapeutic gas. Processor 32, executing a program, reads the oxygen
concentration or purity of the therapeutic gas determined by gas sense
device 48, possibly through analog-to-digital converter 40, and only
commands the second compression stage 26 to be operational when the
oxygen concentration is approximately 90% or above. If the oxygen
concentration falls below approximately 90%, processor 32, executing a
program, turns off the second compression stage 26, and thus ceases
filling the cylinder. In the event oxygen concentration increases again
to approximately 90% or above, the second compression stage 26 (and first
compression stage 24 if it too was turned off (see discussion of FIG. 2
below)) restarts and resumes filling of the portable cylinder.

[0032] The second situation when the second compression stage 26 is turned
off is when filling of the portable cylinder 16 is complete. To this end,
pressure sensor 52 fluidly couples to the therapeutic gas within the
portable cylinder 16 downstream of the flow restrictor 20, and
electrically couples to analog-to-digital converter 40. In accordance
with some embodiments pressure sensor 52 is a part no. MLHO3 KPSP01A
pressure transducer available from Honeywell of Morris Township, N.J.
Thus processor 32, executing a program, senses pressure of the
therapeutic gas within the portable cylinder 16. When the pressure
reaches a predetermined threshold, e.g. 2200 PSI, the fill of the
portable cylinder 16 is complete, and in this situation the second
compression stage 26 is turned off by the processor 32 selectively
asserting or deasserting the associated digital output.

[0033] In spite of the fact that the second compression stage 26 may have
been turned off, either because the oxygen concentration falls below
approximately 90%, or the portable cylinder 16 is full, the first
compression stage 24 may remain operational, providing intermediate
pressure therapeutic gas to the conserver system 28. If oxygen
concentration falls below 85%, the patient is still provided therapeutic
gas, but the patient is notified of the low oxygen concentration by way
of an alarm, and size of the bolus may increase to ensure proper blood
oxygen saturation of the patient. Continuing to supply therapeutic gas in
bolus form reduces the draw on the upstream oxygen concentrator, and may
thus give the oxygen concentrator an opportunity to recover. If the
oxygen concentration continues to drop, therapeutic gas delivery may
transition to a continuous delivery mode, either through one or more
valves of the conserver system 28 and reduced outlet pressure of the
first compression stage 24, or the trans-fill system 1000 may shut off
the first compression stage 24 and supply the patient in a continuous
mode directly from the low pressure therapeutic gas stream (discussed
more fully below with respect to FIG. 2).

[0034] Although the conserver system 28 may be any currently available or
after-developed electronic or pneumatic conserver, in accordance with at
least some embodiments of the invention the conserver system 28 is
implemented utilizing three-port valve 54, three-port valve 56 and a flow
sensor 58. Each three-port valve may be a 5-volt solenoid operated valve
that selectively fluidly couples one of two ports to a common port
(labeled as C in the drawings). Three-port valves 54 and 56 may be
Humphrey Mini-Mizers having part number D3061A available from the John
Henry Foster Company of St Louis, Mo. By selectively applying voltage on
a digital output signal line coupled to the three-port valve 56, the
processor 32 is able to: couple the intermediate pressure therapeutic gas
stream to the common port and therefore to the patient port 30 and
patient; or couple the flow sensor 58 to the common port and therefore to
the patient port 30 and patient. Thus, during the period of time when the
trans-fill system 1000 provides therapeutic gas to the patient,
three-port valve 56 couples the intermediate pressure therapeutic gas
stream to the patient port 30 and also blocks the flow through flow
sensor 58. The length of time that the three-port valve 56 couples the
intermediate pressure therapeutic gas stream to the patient is a function
of the bolus size setting, which may be communicated to the trans-fill
system by way of a user interface 33 coupled to the processor. In some
embodiments, the user interface 33 is a dial-type input (not specifically
shown) where a patient dials in a bolus size setting. In alternative
embodiments, user interface 33 is a key pad or keyboard, and
corresponding display device, where bolus size is supplied to the
processor 32 in digital format.

[0035] In the second valve position of three-port valve 56, flow sensor 58
is fluidly coupled to the patient port 30, and therefore the patient, to
allow sensing of a patient's inhalation. In accordance with some
embodiments of the invention, flow sensor 58 is a flow-through mass flow
sensor having part no. AWM92100V available from Microswitch (a division
of Honeywell). Thus, the flow sensor 58 will not function until gas can
flow through the sensor. Three-port valve 54, in a first valve position,
fluidly couples flow sensor 58 to an atmospheric vent, and thus allows
gas to flow through the flow sensor for measurement purposes. The
three-port valve 54, in a second valve position, couples a blocked port
60 to the common port (the purpose of which is discussed below).

[0036] Consider for the purposes of explanation a trans-fill systems 1000
having at least the first compression stage operational. In the first
configuration of the three-port valves 54 and 56, the flow sensor 58
fluidly couples to the patient port 30, and therefore the patient. As the
patient begins to inhale, processor 32, executing a program, reads or
senses the inhalation through flow sensor 58. When the inhalation is
sensed, processor 32 commands three-port valve 56 to change positions.
Three-port valve 56 thus couples the intermediate pressure therapeutic
gas stream to the common port, and therefore to the patient port 30 and
patient. In this configuration, a bolus of therapeutic gas is delivered
to the patient. For a period of time, determined by the patient's bolus
size setting, the bolus is delivered, and thereafter the processor 32
commands the three-port valve 56 to again couple the flow sensor 58 to
the common port. However, just as valve 56 couples the patient to the
flow sensor 58 to the common port, three-port valve 54 couples the
blocked port 60 to its common port, thus blocking reverse flow of
therapeutic gas through the flow sensor 58. After sufficient time has
passed to allow the therapeutic gas to propagate to the patient and/or to
allow the pressure in the tubing between the trans-fill system and
patient to dissipate, the processor 32 commands the three-port valve 54
to couple the atmospheric vent to its common port, thus allowing flow
through the flow sensor 58, and enabling the processor 32 and flow sensor
58 to sense the next inhalation.

[0037] Although the illustrative embodiment of FIG. 1 shows only one
conserve mode flow path, in alternative embodiments a plurality of
conserve mode flow paths may be present. For example, the trans-fill
system 1000 may individually sense and selectively deliver therapeutic
gas to one or more of the patient's left naris, right naris and/or mouth.
U.S. patent application Ser. No. 10/697,232, titled, "Method and System
of Sensing Airflow and Delivering Therapeutic Gas to a Patient,"
incorporated by reference herein as if reproduced in full below,
discloses a system for individually sensing, and selectively delivering,
therapeutic gas to a patient.

[0038] The trans-fill system of FIG. 1 also comprises a nebulizer port 25
coupled to the intermediate pressure therapeutic gas stream, through
adjustable flow control device 27. Nebulizer port 25 allows a patient to
administer nebulizer treatments, and nebulizer devices may need
therapeutic gas pressures in the 20-35 PSI range. In alternative
embodiments, a patient may perform nebulizer treatments by fluidly
coupling the nebulizer device to the patient port 30 with the valve 56
set to, over the course of the treatment, couple the intermediate
pressure gas stream to the port 30. In these alternative embodiments,
flow control device 27 would fluidly couple between the first compression
stage 24 and the valve 56 or between the valve 56 and the patient port
30.

[0039] FIG. 2 illustrates a trans-fill system 2000 in accordance with
alternative embodiments of the invention. The trans-fill system 2000, in
addition to the capabilities discussed with respect to FIG. 1, has the
ability to provide therapeutic gas to a patient in a continuous flow mode
from the low pressure therapeutic gas stream. In particular, the
trans-fill system comprises a therapeutic gas inlet port 10 that fluidly
couples to compression system 14. Much like the embodiments discussed
with respect to FIG. 1, the compression system 14 comprises a first
compression stage 24 that creates an intermediate pressure therapeutic
gas stream. The intermediate pressure therapeutic gas stream fluidly
couples to both conserver system 28 and the second compression stage 26.
The compression system 14 also comprises a second compression stage 26
that creates a high pressure therapeutic gas stream. The high pressure
therapeutic gas stream fluidly couples to and fills portable cylinder 16
by way of cylinder fill outlet port 21. In some modes of operation, the
trans-fill device 2000 simultaneously fills portable cylinder 16, and
supplies therapeutic gas to a patient using the conserver system 28
through three-port valve 80. Other than the conserver system 28 coupling
to the patient port 30 through the three-port valve 80, operation of the
trans-fill system 2000 in this mode is as described with respect to FIG.
1. Several of the components of FIG. 1, e.g., ges sense device, pressure
sensors and nebulizer port, are not included in FIG. 2 so as not to
unduly complicate the figure, but are inherently present.

[0040] In other modes of operation, the trans-fill system 2000 provides
therapeutic gas to a patient in a continuous flow mode from the low
pressure therapeutic gas stream. In particular, trans-fill system 2000
comprises an adjustable flow control device 82 coupled to the therapeutic
gas inlet port 10. In some embodiments, the adjustable flow control
device 82 allows a patient to set or adjust the mass flow of therapeutic
gas. In alternative embodiments, the adjustable flow control device 82 is
controlled by the processor 32, e.g., processor 32 controlling a
servomotor mechanically coupled to a needle valve. The therapeutic gas
stream whose flow rate is set by the adjustable flow restrictor 82
fluidly couples to a flow sensor 84. Flow sensor 84 could be a part
number AWM43600V available from Microswitch (a division of Honeywell).
Thus, in modes where the trans-fill system 2000 is delivering therapeutic
gas in a continuous flow mode, flow sensor 84 (electrically coupled to
processor 32 by way of the analog-to-digital converter 40) reads the mass
flow and provides the information to a program executing on the processor
32.

[0041] Patients provided therapeutic gas in a continuous flow mode have a
tendency to experience discomfort attributable, to some extent, to nasal
drying effects. Thus, in continuous flow mode it is beneficial to
humidify the therapeutic gas. In accordance with some embodiments,
trans-fill system 2000 comprises a humidifier bottle 86 fluidly coupled
to the low pressure therapeutic gas stream provided to the patient. After
humidification, therapeutic gas couples to the patient port 30 by way of
the three-port valve 80.

[0042] Still referring to FIG. 2, consider the trans-fill system 2000
supplying therapeutic gas to a patient in a continuous flow mode. In this
continuous flow mode, the patient and/or processor 32 may adjust the flow
rate of therapeutic gas using the adjustable flow control device 82. Flow
sensor 84 senses the instantaneous mass flow, and that mass flow may be
read by processor 32. So that the patient too may see the instantaneous
therapeutic gas flow rate, the trans-fill system 2000 comprises a display
device 88 coupled to the processor 32. The display device 88 could be,
for example, a liquid crystal display capable of showing both text and
graphics. In these embodiments, display device 88 couples to the
processor 32 by way of a digital communications port (not specifically
shown). In alternative embodiments, the display device could be a series
of light emitting diodes that illuminate to indicate a particular flow
rate. In these embodiments, the display device 88 couples to the
processor 32 by a digital-to-analog output (not specifically shown) or
the digital output module 38. Regardless of the precise form of the
display device 88, display device 88 communicates to the patient the
instantaneous flow rate of therapeutic gas provided in a continuous flow
mode.

[0043] Depending on the capabilities of the oxygen concentrator or oxygen
source supplying the low pressure therapeutic gas stream, trans-fill
system 2000 may be capable of simultaneously filling portable cylinder 16
and providing therapeutic gas to a patient in continuous flow mode.
Consider, for example, an upstream oxygen concentrator (not shown in FIG.
2) that has the capability of delivering oxygen-enriched gas at a rate of
5 liters per minute (LPM). If the fill rate of the portable cylinder 16
is an illustrative 2 LPM, then the trans-fill system 2000 may be capable
of simultaneously delivering therapeutic gas to the patient in continuous
flow mode of up to 3 LPM while simultaneously filling the portable
cylinder 16. If the patient's continuous flow prescription or setting
exceeds 3 LMP, then trans-fill system 2000 transitions to delivering
therapeutic gas to the patient in a conserve mode. In particular,
processor 32, executing the program, fluidly couples the conserve system
28 to the patient port 30 by commanding the valve position of three-port
valve 80. Thus, in this mode of operation, the trans-fill system 2000
provides a bolus of therapeutic gas to the patient on substantially each
inhalation, with the size of the bolus (length of time that gas is
delivered) based on a bolus size setting communicated to the processor 32
by way of user interface 33. When filling of the portable cylinder is
complete, or where filling has stopped because of low oxygen
concentration, continuous delivery of therapeutic gas may resume.

[0044] In systems where the first compression stage 24 is a diaphragm
pump, flow through diaphragm pump is relatively continuous, and thus a
trans-fill system in accordance with the embodiments above need not have
a low pressure therapeutic gas stream buffer tank. In alternative
embodiments of the invention, the first stage compression device 24 may
be a linear cylinder driven by compressed air. In these embodiments, the
therapeutic gas flow into the linear cylinder may be very cyclic (high
flow as the linear cylinder draws therapeutic gas, and no flow during the
compression stage), and thus a buffer tank on the low pressure
therapeutic gas stream may be needed.

[0045] The above discussion is meant to be illustrative of the principles
and various embodiments of the present invention. Numerous variations and
modifications will become apparent to those skilled in the art once the
above disclosure is fully appreciated. It is intended that the following
claims be interpreted to embrace all such variations and modifications.